Ozone is a an excellent oxidizing agent and is highly destructive to many microorganisms, such as bacteria, fungi and algae. Thus, ozone has found uses in water purification, sterilization and deodorization. In many applications, ozone is more effective than chlorine, while the oxidation product of ozone is typically a harmless and environmentally acceptable gas, such as carbon dioxide or water. However, the high cost and lack of long-term reliable ozone producing equipment has retarded the widespread use of ozone in many commerical applications.
Apparatus generating ozone are sometimes called "ozonators". In a typical corona discharge ozonator, the electrodes are made of aluminum, copper, steel or stainless steel. The dielectric is usually glass, titanium dioxide or alumina, and is eithter attached to one of the electrodes or positioned in close proximity to it. An ozonator design problem has been failure of the dielectric due to mechanical pressure, thermal stresses, high voltage breakdowns, or corrosive attack of the opposing metal electrode. As a consequence, typical corona discharge ozonators have had relatively thick dielectric layers which are disadvantageous in lowering the ozone yields. For example, glass electrode ozonators have typically had a dielectric coating thickness exceeding 2.5 mm (100 mils).
Extremely thin dielectric materials have been suggested for corona discharge ozonators. Thus, U.S. Pat. Nos. 3,984,697, issued Oct. 5, 1976, 3,996,474, issued Dec. 7, 1976, and 3,891,561, issued June 24, 1976, all inventor Lowther, disclose porcelain enamel coatings on electrodes as dielectric material with a thickness on each electrode surface being less than 20 mils (less than 0.5 mm). The Lowther dielectric is formed from a frit with a high titanium content. High titania dielectric materials are relatively expensive and require an increased firing temperature.
Accordingly, there is a need for a durable, efficient and relatively low cost ozone generator, operating on the corona discharge principle, which can produce about 1 to about 5 lbs. (about 0.45 to 2.25 kg) of ozone per day at a favorable overall cost.